Notes for Quiz 5 Paragraph 1 - James Watson’s Mother valued her father’s biological legacy over his material one Paragraph 2 - Watson’s Grandpa died very early - His belief: nurture > nature being shaped to believe that he could make himself into whatever he wanted to be - Example: his grandmother fat =/= he also fat - He doesn’t have the power to prove it as a young teenager - Yet, still believe the evident basics of inheritance Family likeness Paragraph 3,4 Example of traits persist over many: - Habsburg lip: elongation of the jaw and droopiness to the lower lip, for at least 23 generations Hapsburgs arranged marriages between different branches, leading to genetic disease - Last monarchs: could not even chew his food + produce a children Paragraph 5 - Genetic Disease Effect on history / geopolitical impact (e.g. sickness caused the Americans’ against-the-odds military success) - Brutal and tragic consequences Conclusion: the flaws in our genes that cause genetic diseases Para 6 Ancestors: - Application of genetics to practical matters Improving domesticated animals (Milk yield from cattle) Plants (size of fruit) by selective breeding, to produce most productive animals tailor-made for human purposes - Rule of thumb: the most productive cows will produce highly productive offspring - Bateson in 1909 gave the science of inheritance a name: genetics Para 7 Gregor Mendel’s paper was published in 1866 yet being Actual mechanics of ignored for 30/40 years genetics heredity is a major aspect of the natural world readily, universally, observable genetic mechanisms turn out to be complicated Children are not simply a blend of their parent’s characteristics early failure: biologist to distinguish between two fundamentally different processes: heredity and development Heredity / Genetics: parents DNA in the egg and sperm focuses on the INFORMATION Subsequent process: starting point of a single cell to divide developmental biology: the USE of that information Para 8 Greeks and Hippocrates pondered / thought about heredity , and made a theory of pangenesis (supported by Charles Darwin and put forward a modified version) Sex involved the transfer of miniaturized body parts Darwin: each organ contributed gemmules, ultimately exchanged in sexual reproduction gemmules produced throughout an organism’s lifetime, change that occurred in the individual after birth could be passed onto the next generation (however he disproves Lamack’s theory) Darwin: natural selection driving force behind the evolution, NS operated on the variation by pangenesis Para 9 Preformationism contained a complete preformed individual homunculus Para10 Preformationism Avoided the assembly of steps altogether Merely a matter of enlarging homunculus into a fully formed beings regarded as manifestation of the wrath of God, mischief of demons and devils ****Defeated due to better microscopes, never see a tiny homuncules curled up Pangenesis lasted longer gemmules were simply too small to visualize Experiment: cutting the tails off several generations of mice Para 12 Mendel’s 1. experiments were brilliantly designed and painstakingly executed analysis was insightful and deft Approached the problem from a quantitative matter COUNTED, realized the ratios careful experiment and sophisticated quantitative analysis three plant geneticists interested agreed his stance 2. realized specific factors passed from parent to offspring Specific factors are in pairs dominant and recessive genes that the process of receiving the copy of the gene is random Hapsburg Lip dominant, Albinism, recessive character things were transmitted from generation to generation sperm cells only carried a single copy of each of his factors, genes must be on chromosomes (paired factors) hawkweed is not well-suite to breeding experiments low profile existence ended obliged them by smoking twenty cigars a day can’t do field work Morgan Why fruit flies Easy to find Easy to raise and accommodate hundred of flies in a single milk bottle Breeds (reproduction very fast) VS Mendel, no menu of established genetic differences in fly (e.g. green vs yellow, wrinkled vs smooth) Sex is determined chromosomally Eye-color gene is located on the X chromosomes proved the Sutton Boveri Theory Sex-linkage Ex: Hemophilia (X linked recessive) Further: Chromosomes actually break apart and re-form during the production of sperm and egg cells Recombination, shuffle gene copies between membrane of a chromosome pair A break is statistically more likely to achieve when the two genes are far apart Lot of reshuffling long way apart Rare reshuffling closer way HGP Degenerate classes - Perpetuating the inability of the unfortunate to extricate themselves from their blighted circumstances - The rate of reproduction is HUGE! what determines who wins? Genetic variation means that some individuals have advantages to the struggle for existence Middle Classes out reproduced by lower classes The Origin of Species Galton to start a social and genetic crusade namely eugenics - Quantification - Tested the efficacy of prayer ineffectual - Hereditary genius: AN Inquiry into Its Laws and Consequences - improve the human stock by preferentially breeding gifted individuals - good in birth, basic principle of agricultural breeding to humans with conscious choices on who should have children Preformationism defeated up by better microscopes Pangenesis gemmules were simply too small to visualize Chapter 2 Background - Information Most people considered chemistry and physics to be the “real” sciences - Most biologists supposed that proteins would be eventually identified as the primary bearers of genetic instruction - Known DNA exclusively located on chromosomes and had been known for 75 years In 1930s, - DNA is found in “nuclein” - DNA nitrogenous base ATCG revealed - Don’t know how the DNA molecules vary in their sequences, chemically linked. Erwin Scrodinger - Considered that one simple sequence repeated - Written the book What Is Life? - Life could be thought of in terms of storing and passing on biological information - Chromosomes were simply information bearers - Beyond the laws of physics - Impressed Francis Crick and author Author - Disdained the very idea of vitalism Isolation of DNA from - Nuclein was to be found in chromosomes alone pus-soaked bandages - Inheritance ensures a continuity in form from generation to generation - Supporter of chemical heredity theory Composition of the - Fred Griffith surface coats of - Composition of the surface coats of bacteria could be pneumonia bacteria changed - S and R strain different both visually and virulently - R will not infect the mouse due to lack of protein coat - Heat killed S + normal R the MOUSE DIED - A genetic change occurred to the R bacteria! Fred Griffith - 摺友 Culturing bacteria in - Why: much easier to search for the chemical identity test tube of the transforming factor in heat-killed S cells DNA was the transforming principle Response to the view - Mixed response: on DNA being the DNA may to be a complex enough molecule to vast transforming factor quantity of biological information proteins would prove to be hereditary substance 20 letter AA vs Nucleotide 4 Mirsky was very angry Hammarsten Alexander Tdd - Blocked Avery’s chance of getting the Nobel Prize - Produced DNA samples of unprecedent high quality - 1951: (Cambirdge) all chemical bonds linking the nucleotides together are the same backbone of the DNA molecule was very regular Paper - No Two DNA molecules has the same composition - The speed of doing genetic crosses of phages done chromatography Author joining the Phage Group one day could be analyzed the next - Phages were indeed effectively naked genes - DNA shd be understood as a molecular structure in chemical details Herman J muller - Demonstrated that X rays cause mutation X-ray diffraction - A of studying the atomic structure of any molecule that can be crystallized Maurice Wilkins - Unlikely to suggest the structure of DNA - A highly regular crystalline packing - Believed that the DNA’s structure was a helix, however favored three based on his density measurements of DNA fibers. Linus Pauling - Believed that DNA was helical - A form of DNA X-ray Photograph!!!!! - Found the exact arrangement in which chains of amino acids and fold up structure a-helix, alpha helix - Three dimensions schemes – Three Chain Model with sugar phosphate backbones - Phosphate were held together by hydrogen bonds - He didn’t mentioned that DNA is acidic - Matter of simply neglecting to read the existing literature on DNA (esp by Chargaff) Sir Lawrence Bragg and his team confirmed the corrected of Pauling’s a-helix Rosalind Franklin - Incompatible with Wilkins direct and data-focused vs retiring and speculative no model-building could commence before she collected much more extensive diffraction data Crick and Watson - Didn’t believe that DNA was helical - B form of DNA - Failed due to her resistance to model-building - Sketching helical grids on a sheet of paper - Constructure the phosphorous atom model Backbone had to be on the outside but not inside Sir Lawrence Bragg: stop further attempts at building the DNA model Erwin Chargaff Adenine and thymine occurred in roughly equal amounts base sequences on the parental chains would have to be complementary to those on daughter strands Confirmation DNA was the hereditary material DNA must be understood at the molecular level if we were to uncover the essence of the gene confirmed that DNA is a helix structure by photograph (not crystalline) DNA density-measurement slightly favored a twochain Must be hydrogen bond Two strands of double helix (unwind) because most chemists at that time thought DNA too big a molecule to understand by chemical analysis Seymour Benzer Map mutations determine their order produced a map of a single bacteriophage gene showing how a series of mutations were laid out linearly along the virus DNA Unzipping idea Proved the same mechanisms! Nobel Prize Franklin had died of ovarian cancer at 37 Single prize can never be split to more than three ways
